1. Field Of The Invention
The present disclosure relates to an apparatus for controlling a hybrid vehicle and a method thereof. More particularly, the present disclosure relates to an apparatus and a method for controlling a hybrid vehicle that can improve fuel consumption of the vehicle and improve purification efficiency of exhaust gas when a LNT (lean NOx trap) that purifies nitrogen oxide included in exhaust gas is regenerated.
2. Description Of The Related Art
A hybrid vehicle may use two or more power sources, generally, such as an engine and a motor. At this time, a gasoline engine or a diesel engine can be used.
Hybrid vehicles can be manufactured in various structures using two or more power sources of an engine and a motor. The motor in a hybrid vehicle assists the power from the engine in accelerating or uphill driving.
In the hybrid vehicle mounted the diesel engine, since combustion is performed in a state where air excessive ratio is high because of a characteristic of a diesel engine, the exhaust amount of carbon monoxide (CO) or hydrocarbon is small in an exhaust gas unlike a gasoline engine, but nitrogen oxides (hereinafter, referred to as “NOx”) and particulate matter (PM) are exhausted in a great amount.
In order to purify the NOx, a lean NOx trap (LNT) is used. The LNT absorbs nitrogen oxide included in the exhaust gas and causes the nitrogen oxide to react with a reducing agent under predetermined conditions.
The reduced nitrogen oxide is stored at the nitrogen oxide purification device as sulfur compound. The sulfur compound absorbed in the LNT deteriorates the nitrogen oxide purification performance and therefore the sulfur component has to be cyclically eliminated.
The elimination of the sulfur compound in the nitrogen oxide purification device may be called as ‘regeneration’.
In order to perform regeneration of the nitrogen oxide purification device, the engine should be maintained constant regeneration condition. For example, an engine RPM should be within a predetermined rotation speed, and an engine torque should be within a predetermined torque. If the regeneration condition is not constantly maintained when the nitrogen oxide purification device is regenerated, regeneration efficiency is deteriorated, and number of regeneration and regeneration time are increased.
Further, when the nitrogen oxide purification device is regenerated, post injection is performed in order to exhaust gas is to be enrichment state. However, fuel injected by the post injection does not contribute to engine torque, therefore there is a problem that fuel consumption of vehicle is increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form prior art that is already known in this country to a person of ordinary skill in the art.